The importance of first void urine for testing infection


Q: How important is first-void urine for testing infections such as Chlamydia or Gonorrhea? I gave a urine test, but it was not first void and my results were negative. Of four tests I gave, two were sent to the lab for Chlamydia/Gonorrhea testing and two were tested with a dipstick for general infection. All four came back negative, however all four were not first-void urine. Is the test so sensitive that it needs first-void? I am a upset that my doctor did not ask this of me if it is important for this test.

Symptoms:  Burning urination, discharge, delayed urine, cloudy urine, weak urine flow

A:   Hello,
Thanks for contacting for an opinion.

The first void sample is the best sample collected early morning which should be used for rapid testing for diagnosing urogenital Chlamydia trachomatis infection in men and gonorrhea. The sensitivity of the first void urine sample to detect the infection is around 47 % higher as compared to even the mid -stream sample.
The reason is that both the chlamydia and gonorrhea harbor the urethra of male in the genital tract and the concentration is maximum in the early morning void . Hence the chances of detection are also higher with the first sample in the morning without discarding the initial urine.
So , it is suggested that you may repeat the test again after 3 days with the early morning sample to remove the bias. But if the test has been done with the NAAT technique, then this test has been found to be equally sensitive with the mid-stream urine as well. So, you may discuss the type of test with your physician and ask for a repeat test, preferably NAAT test if possible if the lab has done the rapid test only.
I Hope i have answered your query in detail,
wishing you good health,

Comments / Follow Ups

Patient: Thank you for the answer. What is the NAAT technique?
Patient: Also, what is considered to be mid-stream sample?
Doctor: Nucleic acid amplification tests (NAATs) have created a revolution in our ability to diagnose chlamydial infections. They are markedly more sensitive (while maintaining exquisite specificity) than previously used tests.The leading deterrent to the acceptance of NAATs has been their perceived cost.

The midstream sample is the one where the initial voided urine is discarded and the sample is taken during flow of urine or while urinating.
Patient: If the urine was sent out to a lab for testing with a result in 3-5 days, is this most likely using the NAAT method?
Doctor: It is possible then if it took 5 days , then it may be the NAAT method. However you may confirm it from the lab directly . This shall remove any doubts or it should be mentioned in the report itself. You may check please.

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